Disc storage devices are used in data processing systems for storing large amounts of information that can be accessed in milliseconds. Storage or retrieval of information is accomplished by a disc drive system which includes one or more read/write (R/W) heads or "sliders" to read/write data from/to one or more discs.
A disc drive system stores data on rotating media, for example a magnetic disc, and uses read/write heads suspended on a moving armature which read/write the data on the rotating media as the surface of the rotating media moves past them. The interface between the heads and the disc surface is extremely delicate.
It is known that all physical parts of the disc drive system posses resonant vibrational modes, where, if a frequency equal to the resonant mode frequency is applied to the system, the part will resonate and amplify the initial exciting frequency. The spindle/disc pack also possesses such modes. When the spindle/disc pack is excited, typically by externally generated shock loads, it can generate a large amount of movement of the disc surface relative to the read/write heads. This prevents the heads from reading/writing the correct tracks on the disc surface and may result in the disc drive controller inhibiting a write or read, known as a write protect/write unsafe or a read protect/read unsafe. When the duration of the disturbance is prolonged, a write or read fault is declared, i.e. the disc drive indicates that it cannot write or read the data, despite repeated attempts. As a result, a fatal condition occurs. When the disc drive is properly mounted in a computer console or case, such impact loads are usually minimized. However, when the drive is removed or handled prior to installation in the cabinet bay or case, the situation is different. Dropping the drive can severely damage the delicate disc/head interface.
When a mechanical shock load is experienced by a hard disc drive, for example, by the user hitting the drive or dropping the drive prior to or during handling while installing the drive in the computer case or laptop computer, the spin motor in the hard disc drive receives this shock and transmits the shock received by the housing to the discs. If the frequency of the shock coincides with a resonance characteristic of the housing and/or the HDA, the transmitted shock load may be substantial. Since each of the sliders rests on the surface of one of the discs, the shock induced vibrations may cause surface to slider contact with potentially detrimental damage to the discs and/or sliders. Consequently, it is desirable to minimize the effects of external shock loads on the drive when the drive is not installed in the computer case or rack. One solution is to provide a rubber gasket between the base of the disc drive housing and the spin motor support in the disc drive housing, which dampens transmission of shock loads. However, this solution has the drawback of requiring additional assembly parts and therefore adds an additional cost to the apparatus.
Another problem that arises is one associated with the return of allegedly defective drives to the manufacturer. Sometimes a user/purchaser may drop a drive on the ground, then install the drive, and then find out that the drive no longer reads or writes data properly. The user then typically returns the drive to the dealer or manufacturer for a replacement drive. There is presently no built in mechanism in disc drives to accurately determine whether the drive has been subjected to unacceptably high shock loads during handling.
The present invention provides solutions to the above and other problems and offers advantages over the prior solutions to the above and other problems. These and various other features as well as advantages which characterize the present invention will be apparent upon reading of the following detailed description and review of the associated drawings.